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<html>
  <head>
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
    <meta name='mobile-web-app-capable' content='yes'>
    <meta name='apple-mobile-web-app-capable' content='yes'>

    <!-- Origin Trial Token, feature = WebXR Device API, origin = https://immersive-web.github.io, expires = 2018-08-28 -->
<meta http-equiv="origin-trial" data-feature="WebXR Device API" data-expires="2018-08-28" content="AnNpu7ceXvLew05ccD8Zr1OZsdZiB2hLQKK82kTTMDwF7oRKtP3QEJ4RzkeHrmB8Sq0vSV6ZNmszpBCZ0I8p9gAAAABceyJvcmlnaW4iOiJodHRwczovL2ltbWVyc2l2ZS13ZWIuZ2l0aHViLmlvOjQ0MyIsImZlYXR1cmUiOiJXZWJYUkRldmljZSIsImV4cGlyeSI6MTUzNTQxNDQwMH0=">

    <title>Input Tracking</title>

    <link href='css/common.css' rel='stylesheet'></link>

    <!--The polyfill is not needed for browser that have native API support,
        but is linked by these samples for wider compatibility.-->
    <!--script src='https://cdn.jsdelivr.net/npm/webxr-polyfill@latest/build/webxr-polyfill.js'></script-->
    <script src='js/xrray-polyfill.js' type='module'></script>
    <script src='js/webxr-polyfill.js'></script>

    <script src='js/webxr-button.js'></script>
  </head>
  <body>
    <header>
      <details open>
        <summary>Input Tracking</summary>
        <p>
          This sample demonstrates basic tracking and rendering of
          XRInputSources. It does not respond to button presses or other
          controller interactions.
          <a class="back" href="./index.html">Back</a>
        </p>
      </details>
    </header>
    <script type="module">
      import {Scene} from './js/cottontail/src/scenes/scene.js';
      import {Renderer, createWebGLContext} from './js/cottontail/src/core/renderer.js';
      import {Gltf2Node} from './js/cottontail/src/nodes/gltf2.js';
      import {QueryArgs} from './js/cottontail/src/util/query-args.js';
      import {FallbackHelper} from './js/cottontail/src/util/fallback-helper.js';
      import {SkyboxNode} from './js/cottontail/src/nodes/skybox.js';
      import {vec3} from './js/cottontail/src/math/gl-matrix.js';

      // If requested, initialize the WebXR polyfill
      if (QueryArgs.getBool('allowPolyfill', false)) {
        var polyfill = new WebXRPolyfill();
      }

      // XR globals.
      let xrButton = null;
      let xrImmersiveRefSpace = null;
      let xrNonImmersiveRefSpace = null;

      // WebGL scene globals.
      let gl = null;
      let renderer = null;
      let scene = new Scene();
      scene.addNode(new Gltf2Node({url: '../media/gltf/cave/cave.gltf'}));
      scene.addNode(new SkyboxNode({url: '../media/textures/eilenriede-park-2k.png'}));
      scene.standingStats(true);

      function initXR() {
        xrButton = new XRDeviceButton({
          onRequestSession: onRequestSession,
          onEndSession: onEndSession,
          supportedSessionTypes: ['immersive-vr']
        });
        document.querySelector('header').appendChild(xrButton.domElement);

        if (navigator.xr) {
          requestInlineSession()
          .then((session) => {
            gl.canvas.addEventListener('touchend', () => {
              session.end().then(() => {
                requestInlineSession({ optionalFeatures: ['local-floor'] });
              }, { once: true });
            })
          });
        } else {
          initFallback();
        }
      }

      function initFallback() {
        initGL();
        let fallbackHelper = new FallbackHelper(scene, gl);
        fallbackHelper.emulateStage = true;
      }

      function initGL() {
        if (gl)
          return;

        // Note: If you don't want dragging on the canvas to do things like
        // scroll or pull-to-refresh, you'll want to set touch-action: none;
        // on the canvas' CSS style, which this page does in common.css
        gl = createWebGLContext({
          xrCompatible: true
        });
        document.body.appendChild(gl.canvas);

        function onResize () {
          gl.canvas.width = (gl.canvas.offsetWidth * window.devicePixelRatio);
          gl.canvas.height = (gl.canvas.offsetHeight * window.devicePixelRatio);
        }
        window.addEventListener('resize', onResize);
        onResize();

        renderer = new Renderer(gl);

        scene.setRenderer(renderer);

        // Loads a generic controller mesh.
        scene.inputRenderer.setControllerMesh(new Gltf2Node({url: '../media/gltf/controller/controller.gltf'}));
      }

      function onRequestSession() {
        navigator.xr.requestSession('immersive-vr', {requiredFeatures: ['local-floor']}).then((session) => {
          session.mode = 'immersive-vr';
          xrButton.setSession(session);
          onSessionStarted(session);
        });
      }

      function requestInlineSession(options) {
        return navigator.xr.requestSession('inline', options)
          .then((session) => {
            session.mode = 'inline';
            return onSessionStarted(session);
          });
      }

      function onSessionStarted(session) {
        session.addEventListener('end', onSessionEnded);

        initGL();

        session.updateRenderState({
            baseLayer: new XRWebGLLayer(session, gl)
        });

        session.requestReferenceSpace('local-floor').then((refSpace) => {
          return refSpace;
        }, (e) => {
          if (!session.mode.startsWith('immersive')) {
            // If we're in inline mode, our underlying platform may not support
            // the local-floor reference space, but a viewer space is guaranteed.
            return session.requestReferenceSpace('viewer').then((viewerRefSpace) => {
              // Adjust the viewer space for an estimated user height. Otherwise,
              // the poses queried with this space will originate from the floor.
              let xform = new XRRigidTransform({x: 0, y: -1.5, z: 0});
              return viewerRefSpace.getOffsetReferenceSpace(xform);
            });
          } else {
            throw e;
          }
        }).then((refSpace) => {
          if (session.mode.startsWith('immersive')) {
            xrImmersiveRefSpace = refSpace;
          } else {
            xrNonImmersiveRefSpace = refSpace;
          }

          session.requestAnimationFrame(onXRFrame);
        });

        return session;
      }

      function onEndSession(session) {
        session.end();
      }

      function onSessionEnded(event) {
        if (event.session.mode.startsWith('immersive')) {
          xrButton.setSession(null);
        }
      }

      function updateInputSources(session, frame, refSpace) {
        let inputSources = session.inputSources;

        for (let inputSource of inputSources) {
          // If we have a grip matrix use it to render a mesh showing the
          // position of the controller.
          // Based on https://github.com/immersive-web/webxr/blob/master/input-explainer.md#placing-renderable-models
          if (inputSource.gripSpace) {
            let pose = frame.getPose(inputSource.gripSpace, refSpace);
            if (pose) {
              scene.inputRenderer.addController(pose.transform.matrix);
            }
          }

          // We may not get a pose back in cases where the input source has lost
          // tracking or does not know where it is relative to the given frame
          // of reference.
          // Based on https://github.com/immersive-web/webxr/blob/master/input-explainer.md#targeting-ray-pose
          let pose = frame.getPose(inputSource.targetRaySpace, refSpace);
          if (pose) {
            let targetRay = new XRRay(pose.transform);
            if (inputSource.targetRayMode == 'tracked-pointer' &&
                !pose.emulatedPosition) {
              // If we have a pointer matrix and the pointer origin is the users
              // hand (as opposed to their head or the screen) use it to render
              // a ray coming out of the input device to indicate the pointer
              // direction.
              // Only show the laser when the position is not emulated, so that
              // it's easy to know that value while still in VR.
              scene.inputRenderer.addLaserPointer(targetRay);
            }

            // If we have a pointer matrix we can also use it to render a cursor
            // for both handheld and gaze-based input sources.

            // Statically render the cursor 2 meters down the ray since we're
            // not calculating any intersections in this sample.
            let cursorDistance = 2.0;
            let cursorPos = vec3.fromValues(
                targetRay.origin.x,
                targetRay.origin.y,
                targetRay.origin.z
                );
            vec3.add(cursorPos, cursorPos, [
                targetRay.direction.x * cursorDistance,
                targetRay.direction.y * cursorDistance,
                targetRay.direction.z * cursorDistance,
                ]);

            scene.inputRenderer.addCursor(cursorPos);
          }
        }
      }

      function onXRFrame(t, frame) {
        let session = frame.session;
        let refSpace = session.mode.startsWith('immersive') ?
                         xrImmersiveRefSpace :
                         xrNonImmersiveRefSpace;
        let pose = frame.getViewerPose(refSpace);

        scene.startFrame();

        session.requestAnimationFrame(onXRFrame);

        updateInputSources(session, frame, refSpace);

        scene.drawXRFrame(frame, pose);

        scene.endFrame();
      }

      // Start the XR application.
      initXR();
    </script>
  </body>
</html>
